I'm not sure corrosive is the word i am looking for. But i have a motorcycle that has a black satin textured finish on the engine. I have noticed that over time the finish seems to have become less receptive to dressings. I've used back to black on it and another silicone spray especially for bikes. These products used to leave the finish looking factory new and stayed that way for weeks. Now it seems as tho the dressing don't go on as well or last as long. I clean the bike with simple green automotive grade and soak it down then wash it off with a hose and follow up with the dressings. I'm thinking the simple green may be to blame because i've heard things about how it is acidic or corrosive or some such thing. Could be the dressings i suppose, but in any case do you have any thoughts on a cleaning solution that i can spray on, let sit, then hose off? There are too many nooks and crannies on a bike to use car wash and scrub it. This method with SG is quick and very effective. But i want to start researching what products to use that will not eat away at the finish at a microscopic level and make it have that less than showroom new look.